It is a well known problem with any beverage producing device having an integrated heater, e.g., a thermoblock or heating cartridges, that limestone scale is prone to deposit on the heating/heated contact surfaces with the circulated water or steam. The water scale comes essentially from water insoluble solid, i.e., calcium carbonate that formed from calcium ions and carbonate ions which react together and precipitate. The deposition increases in hot water because calcium carbonate is less soluble in hot water than in cold water. Therefore, the degree of deposition of calcium carbonate solid can be dependent on the content of these ions in water, also called “water hardness” but also on the water temperature, the frequency of use of the machine, and other factors.
To descale the beverage preparation machine, it is known to periodically have a decalcifying agent be passed through the water contact surfaces of the fluid circuit of the machine, e.g., heaters, tubings, water/steam injecting nozzle or needles, etc. The descaling agent (e.g., a chemical composition comprising acetic acid, phosphoric acid and/or a phosphonic acid) dissolves the scale that forms on the surfaces of the machine. After having passed the descaling agent, it is necessary to have a certain volume of clear water be circulated in the fluid circuit of the machine to eliminate taste perceptible trace of descaling agent that may affect the taste of subsequently produced beverages.
Therefore, a typical procedure for descaling a beverage producing device, e.g., a coffee machine, consists in mixing an effective dose of descaling agent with water in the water reservoir of the machine to form a descaling aqueous mixture, circulating the descaling aqueous mixture in the fluid circuit of the machine, rinsing the fluid circuit with clear water filled into the reservoir when the effective descaling agent has been fully circulated. This procedure requires several manual operations and a periodic surveillance from the user who achieves these different operations. In particular, the user must fill the reservoir with water twice, collect and also discard the liquid waste twice at the collecting side of the machine, i.e., at the beverage discharge outlet. This also requires several switches-on/switches-off on the board for controlling by the pump the circulation of water. Therefore, it is fastidious for the user to stay in front of the machine until the descaling procedure is completed. Another problem comes from a difficulty to control the effective quantities of the descaling agent and of the rinsing liquid. Therefore, the effectiveness of the method highly depends on the respect of these quantities by the user himself.
W02006/090183 relates to a beverage dispenser comprising a clean-in-place system wherein the cleaning fluid is pumped from a storage area to the beverage line. The cleaning operation is carried out automatically in response to a predetermined event. However, the cleaning agent is not directly placed in the beverage line and it so requires to be pumped in the beverage line by pumping means.
Therefore there is an advantage to propose a solution that eases the descaling procedure, in particular, makes it simpler to use, requires less attention from the user and is also better controlled for an improved descaling efficiency.
For this, the invention relates to a beverage preparation device comprising:
a fluid circuit comprising a water reservoir, a water pump, an in-line heating means designed for heating circulating water, a beverage producing module, which are fluidically connected for circulating water from the reservoir to the beverage producing module, wherein an in-line descaling system is provided in the fluid circuit downstream of the reservoir, comprising a dedicated compartment arranged for receiving a predetermined dose of a water soluble/dispersible descaling agent and a water inlet and water outlet for water to circulate through the compartment.
Therefore, a dedicated descaling agent reserve is arranged in the fluid circuit, downstream of the water reservoir, so that a predetermined quantity of water of the water reservoir can be utilized both for descaling purpose and for rinsing purpose. This arrangement is such that there is no need to refill the water tank with clear water since the water thank is not directly contaminated with the descaling agent.
In a mode, the compartment is fluidically placed between the water reservoir and the pump. In particular, a one-way valve is interposed between the water reservoir and the compartment; wherein the valve is allowed by design or actively controlled to open only when water is drawn from the water reservoir to the compartment, e.g., by suction effect of the pump which opens the valve.
Therefore, a back-flow of the descaling agent in the reservoir containing clear water can be prevented when the pump is stopped, for instance, during pause(s) in the descaling procedure. Therefore, the continuous descaling-rinsing procedure can be carried out successfully without intervention from the user for rinsing or refilling the water tank. The one-way valve can be a passive valve such as a rubber-elastic slit valve or such as a ball spring-biased valve. The one-way valve can also be an electromagnetic valve controllable in opening/closing by the control unit of the device. The valve can be placed in a wall that separates the water reservoir from the descaling compartment. The wall can advantageously be the bottom wall of the water reservoir and/or an entry wall of the compartment.
In a particular mode, for reducing the complexity of the device, the reservoir and the compartment can be placed adjacent one another. For example, the compartment and the reservoir have complementary stacking means for enabling the reservoir to be stacked on the compartment. Water sealing means can further be provided between the stacking means. Sealing means can be an O-ring of rubber elastic material.
In a possible alternative solution, the compartment is placed between two portions of hose and fluidically distant from the water reservoir.
In a possible embodiment, the compartment for the descaling agent is fluidically placed between the pump and the in-line heating means. In this case, the compartment and its connections to the fluid circuit must resist to the fluid pressure exerted in this pressurized portion of the fluid circuit to the repeated beverage brewing and descaling cycles.